This invention relates to a flow shut-off device for a tube formed of flexible material and adapted to carry a fluid. Such devices are used for many different purposes, and while the device may be employed with tubes carrying liquids as well as gases, the device of the invention is especially adapted for use with tubes in which a gas, such as air, is carried. Still more specifically, such devices are of particular applicability to tubes carrying an air stream with suspended abrasive particles therein, such as used in machining operations, dental work and the like. For such abrasive purposes, the flow tube is repeatedly opened and closed in carrying out the desired abrasive operation.
In devices of the kind referred to, a relatively small diameter tube formed of flexible material, such as plastic materials, is commonly employed, and it has been known to effect shut-off of the flow by mechanically pinching the tube. With known prior art pinch shut-off devices, the tube has a tendency to deteriorate relatively rapidly.
The present invention provides an improved tube shut-off device, and it is a principal object of the present invention to provide a pinch tube shut-off type of device in which the life of the tube is greatly extended as compared with prior art arrangements, because of the manner in which the tube shut-off is effected.